The IRS lays out a guideline for family loans which I think is the AFR, which is usually below the market rates.My understanding with regard to 1031 transactions is that the party needs to be the same on both sides. 

Usually, the two figures together result in a realistic price.

It is also becoming popular for business looking to exit the "failing" state of Illinois while not moving too far from their usual base. 

Or could we just both sign a usual assignment contract together?

(not so important but if they only require 15% down on a single family home that is usually a good sign that you are working with a flexible lender) Can I change title to my LLC?

Use a general warranty deed so it does not cloud title for future sales. as you state this is usually in the Alienation of title clause.. and gives the holder of the debt the right to call. 

You can rent long term as a "Alojamento Local", which is what's usually used for Airbnbs and short term rentals, given the fact that you do not have an upper limit on the amount of times you can renew the service or the duration.

Credit unions usually have more reasonable rates/closing fees and are generally more upfront about what they charge.  

10.How long does it usually take you to fill a vacancy?

It took a bit longer to close than a usual off-market cash deal but we got it done!